1. Field of the Invention
A method and apparatus to produce a colloidal mixture.
2. Description of the Prior Art
As is well recognized in the construction and building industry concrete is used generically to define a collection or aggregation of materials which together form a reasonably continuous and consistent solid when cured. In conventional applications of concrete products, voids and/or small discontinuities or inclusions of air within the resulting product are considered to be highly undesirable. This is true since such voids normally affect the operating or performance characteristics of the product in a harmful manner.
The following U.S. Pat. Nos. disclose prior art products or cementitious material which is generally applicable but clearly distinguishable from the product which is formed through the utilization of the method and apparatus of the present invention: 2,710,802 to Lynch, 3,583,88 to Moore, 1,665,104 to Martienssen, 3,196,122 to Evans, 3,240,736 to Beckwith, 3,360,493 to Evans, 3,429,450 to Richards, 3,477,979 to Hillyer, 3,687,021 to Hinsley, 3,690,227 to Weltry, 3,870,422 to Medico, 2,130,498 to Klemschofski, 3,822,229 to McMasters, 954,511 to Gordon, 2,851,257 to Morgan, 3,877,881 to Ono, 4,225,247 and 4,225,357 to Hodson.
The products of the type generally disclosed in the above set forth U.S. patents frequently suffer from certain inherent disadvantages. Such disadvantages include failure under heavy load, stress conditions and excessive cost as in highway construction. However, there is an acknowledged need in the construction industry, especially in the area of building roads, highways and bridges for a concrete type product at a reasonable cost and able to stand high load or stress conditions for high speed operation of large or heavy motor vehicles.
Both in pervious and non-pervious concrete, a high shear mixer may be used to produce a cement-water component of high strength and increased viscosity resulting in a high strength structure. However, the process of combining or mixing cement and water can be carried much further, although not necessarily of benefit in pervious concrete, since a greater intensity of fine particle mixing produces a cement-water combination of paint-like consistency, which sets to a gloss-like surface, not appropriate to pavement.
With proper techniques, such a super-mixed mortar can be directly sprayed, painted or otherwise applied to cement products, and with proper curing processes produces a surface which is more durable than normal concrete, and which has an appearance similar to glazed ceramic tile. By the use of white cement, in place of grey, and standard organic mineral colors, many decorative effects can be obtained. Experience has shown that the surface produced is extremely durable, although its Mohr hardness value is below the level of kiln-fired ceramics. For example, it can be scratched by martensitic steel if a blade or tool is applied with sufficient pressure, or by abrasion with silicone compounds.
In explanation of this result, it appears that, in general, high energy mixing further colloidalizes the cement: water fraction, and produces a new mortar form proportional to the intensity of mixing which results in combination and hydration superior to that accomplished by present mixing methods. It should be noted that the limitation of particle fineness in cement clinker grinding during production, as presently practiced, is to prevent shrinkage, surface crazing, cracking and flash setting thought to be an uncontrolled hydration effect.
However, the colloidalized mortar shows no signs of such defects. Apparently, the colloidalizing process accelerates hydration exothermic behaviour so as not to protract heat loss and shrinkage factors in the setting phase. At the same time it appears to produce more of the strength intrinsically available from the hydration of cement as indicated by the known ability to re-grind set concrete, which may then be mixed with water, when it will again generate some setting strength illustrating its full potential is not reached in normal concrete practice.
Assuming a strength increase as high as may be expected from recognized re-grinding and remixing data, it should be possible to considerably reduce the cement content of concretes and still obtain comparable strengths. In addition, this idea can be extended to the use of pozzolanic additives, particularly fly ash, which is a by-product of coal-fired furnaces. This will further reduce the cement consumption. It may ultimately be possible to use a lime and fly ash to completely replace cement, without the use of partial fusion, as now practiced in cement production.
It is readily believed that the inherent deficiencies set forth above are due to a failure to fully form the hydrated product when utilizing conventional or currently known techniques as in the formation of substantially conventional concrete utilizing conventional cement, water and aggregate components in a manner which will result in more favorable operating and performance characteristics.